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Quarrying
Introduction
Quarried products are used in the building and construction industries and are essential components for providing shelter and infrastructure. In Queensland, particularly during the past 25 years, the trend has been for annual production of quarried products to increase. The quarry industry is market driven and therefore is focused on price, quality and service. Although the industry is dominated by a few large, national, vertically integrated companies, independent operators such as the Barro Group provide competition, market choice and special services and contribute to a vital and vigorous industry.
Quarried Products Uses and Specification
The term heavy construction materials is used to denote all low-cost quarried hardrock, sand, gravel, and other earth materials which are extracted in bulk and used for construction purposes.
Natural construction materials are extracted from deposits of hard, durable, and dense rock (Hardrock Quarries) and from deposits of sand and gravel (Gravel Quarries or Pits).
Hardrock Quarries produce road screenings, coarse aggregate, fine aggregate, road base, armour rock, rip rap, railway ballast, drainage materials, landscaping materials, filters and fills. The great bulk of quarried products is used in road construction (embankments, sub-base, base, wearing course, asphalt, screenings, drainage media, shoulder gravels) and in concrete and concrete products (aggregate).
Natural gravel and crushed rock can be interchanged as a concrete coarse aggregate. Natural sands and gravels are generally preferred as fine aggregate and have particular applications for architectural finishes and for exposed aggregate. However, sand manufactured from hard rock is partially replacing natural sand as a source of fine aggregate.
Hardrock deposits are preferred for the manufacture of road base, asphalt aggregate, and road surface screenings.
Quarried products require characteristics that ensure their serviceability for the engineered design life. In general, a rock suitable for use as coarse aggregate should be sound, durable, resistant to abrasion and chemical attack, and be relatively free of deleterious materials. Crushing behaviour, density, hardness and other characteristics such as surface characteristics, colour, and skid resistance, are important factors for particular uses, e.g. skid resistant road surfacing.
Characteristics required of concrete aggregates are set out in Australian Standard AS2758.1-1985: Aggregates and Rock for Engineering Purposes, Part 1, Concrete Aggregates.
The Queensland Main Roads Department's manual of Standard Specifications sets out the requirements for quarried products used in road construction throughout Queensland.
Demand
The demand for quarried products is derived from building and construction. Homes, hospitals, educational institutions, commercial buildings, manufacturing plants, warehouses, sporting facilities, shopping centres and most economic activities that require shelter and storage rely on quarried products.
Quarried product is widely used in concrete, predominantly in the form of fine and course aggregate.
Infrastructure such as water supply, drainage, telecommunications, waste water collection and treatment, electricity, airports, seaports, roads, bridges, railways as well as affordable housing, public works and economic prosperity all depend upon convenient and economical supplies of aggregates and other quarried product. It is important that a community finds a source of quarried product close by, otherwise the cost of transportation dramatically increases the cost of construction.
In South-East Queensland each man, woman and child consumes about 10 tonnes of quarried product per year (as compared with two tonnes of food per year), so there is a large demand for quarried product. The existing sources are being depleted and demand grows with increasing population.
Protection of Extractive Resources
Because the demand for quarried material is high and increasing in Queensland (especially in South East Queensland), Government is taking steps to protect quality sources of construction material from incompatible uses, such as residential uses. This has resulted in the development of the Draft State Planning Policy for the Protection of Extractive Resources (see Documentation).
One hundred KRAs (Key Resource Areas) have been identified in Queensland, which includes Mount Cotton as shown in the map below. Barro Group's quarry is in the south-eastern part of the map.
Mount Cotton Key Resouce Area
(Click to enlarge)
KRAs are considered critical to the development of our State; however, so is the preservation of koalas and other wildlife. With appropriate management we are implementing a win-win solution, whereby we can extract the needed material while simultaneously improving conditions for koalas and other wildlife at the site.
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